| 桂北地区南华系沉积物源分析——来自碎屑锆石U-Pb年龄的证据 |
| |
| 引用本文： | 韩坤英,王梁,丁孝忠,任留东,高林志,刘燕学,庞健峰,薛玖红.桂北地区南华系沉积物源分析——来自碎屑锆石U-Pb年龄的证据[J].岩石学报,2016,32(7):2166-2180. |
| |
| 作者姓名： | 韩坤英 王梁 丁孝忠 任留东 高林志 刘燕学 庞健峰 薛玖红 |
| |
| 作者单位： | 中国地质科学院地质研究所, 北京 100037,中国地质科学院地质研究所, 北京 100037,中国地质科学院地质研究所, 北京 100037,中国地质科学院地质研究所, 北京 100037,中国地质科学院地质研究所, 北京 100037,中国地质科学院地质研究所, 北京 100037,中国地质科学院地质研究所, 北京 100037,江苏省水文地质海洋地质勘查院, 淮安 223005 |
| |
| 基金项目： | 本文受科技基础性工作专项（2011FY120100）和中国地质调查局地质调查项目（1212011120115）联合资助. |
| |
| 摘 要： | 江南造山带西南部是扬子克拉通新元古代地层发育较完整的地区之一。其中,桂北地区的南华系地层自下而上依次为:长安组、富禄组、大塘坡组和黎家坡组,沉积厚度从几十米到几千米不等,总体趋势是西厚东薄。本文对长安组、富禄组、黎家坡组的5个样品进行了碎屑锆石LA-ICP-MS U-Pb年龄测试。其中长安组碎屑锆石U-Pb年龄存在一个峰值,峰值区间为724~972Ma之间,最年轻的年龄加权平均值为746±5Ma(n=19),指示南华系长安组沉积年龄可能介于746~780Ma之间;富禄组碎屑锆石U-Pb年龄有三个峰值,主峰为705~936Ma,两个次峰分别为1823~2163Ma和2241~2673Ma之间;黎家坡组下部121109-3样品的碎屑锆石主峰值为1966~2118Ma,两个次峰为724~921Ma和2221~2688Ma;中部121109-4样品碎屑锆石主峰值为1813~2192Ma,两个次峰为748~944Ma和2296~2726Ma;上部121109-5样品碎屑锆石主峰值为1984~2193Ma,两个次峰为653~1007Ma和2215~2675Ma。桂北地区南华系长安组、富禄组、黎家坡组5个样品的年龄峰值区间相近,但主峰和次峰有明显的区别,反映了三个组沉积地层主要物源可能来自不同的地区,并经历了不同的沉积环境。碎屑锆石年龄分布特征反映了在653~1007Ma之间扬子克拉通东南缘、江南造山带西南部的桂北地区有强烈的岩浆活动,可能与Rodinia超大陆的聚合和裂解事件有关,而1792~2261Ma的岩浆活动则与Columbia超大陆的聚合和裂解事件相对应,2298~2500Ma碎屑锆石年龄可能暗示在扬子克拉通南缘存在古元古代基底,少量大于2500Ma的锆石年龄表明在扬子克拉通南缘还存在太古宙基底物质。5个样品均缺少1100~1300Ma格林威尔造山时期的记录,说明江南造山带并非处在Rodinia超级大陆的中心。总之,扬子克拉通南缘及江南造山带西南部至少经历了三期强烈的构造-岩浆热事件,这三期事件在桂北地区的南华系沉积地层中均有非常清楚的记录。
|
| 关 键 词： | 碎屑锆石 U-Pb年龄 南华系 江南造山带 |
| 收稿时间： | 2015/3/31 0:00:00 |
| 修稿时间： | 2015/10/15 0:00:00 |
Provenance of sedimentary rocks of Nanhua System in the northern Guangxi Province: Evidence from detrital zircon U-Pb ages |
| |
| HAN KunYing,WANG Liang,DING XiaoZhong,REN LiuDong,GAO LinZhi,LIU YanXue,PANG JianFeng and XUE JiuHong.Provenance of sedimentary rocks of Nanhua System in the northern Guangxi Province: Evidence from detrital zircon U-Pb ages[J].Acta Petrologica Sinica,2016,32(7):2166-2180. |
| |
| Authors: | HAN KunYing WANG Liang DING XiaoZhong REN LiuDong GAO LinZhi LIU YanXue PANG JianFeng and XUE JiuHong |
| |
| Institution: | Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China,Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China,Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China,Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China,Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China,Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China,Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China and Jiangsu Province Hydrogeology and Marine Geological Exploration, Huai''an 223005, China |
| |
| Abstract: | The southwestern Jiangnan Orogenic is one of the regions in the Yangtze craton where the Neoproterozoic strata well developed. The Nanhua System in the northern Guangxi Province is composed of the Chang''an, Fulu, Datangpo and Lijiapo formations in the ascending sequence. The strata thickness range from tens of meters to several kilometers and there is a general tendency toward decreasing thickness from west to east. In this paper, detrital zircons U-Pb ages from 5 samples of the Chang''an, Fulu and Lijiapo formations were analyzed by LA-ICP-MS method. The detrital zircon U-Pb ages of the Chang''an Formation display a age peak between 724Ma and 972Ma and the weighted average age of the youngest zircons is 746±5Ma (n=19), indicating that the Chang''an Formation of the Nanhua System may be deposited between 746Ma and 780Ma; For the Fulu Formation, detrital zircon U-Pb ages have three peaks with the main peak at 705~936Ma and two sub-peaks at 1823~2163Ma and 2241~2673Ma; detrital zircons from the lower Lijiapo Formation (Sample 121109-4) have a major peak at 1966~2118Ma and two sub-peaks at 724~921Ma and 2221~2688Ma. Sample 121109-4 of the middle Lijiapo Formation is featured by the major age peak of 1813~2192Ma and two sub-peaks of 748~944Ma and 2296~2726Ma; For the upper Lijiapo Formation, Sample 121109-5 is characterized by the major age peak of 1984~2193Ma and two sub-peaks of 653~1007Ma and 2215~2675Ma. Detrital zircon age ranges of the 5 samples from the Chang''an, Fulu and Lijiapo formations of the Nanhuan System in the northern Guangxi Province are similar, but the main peaks and the sub-peaks are significantly different, reflecting their different provenance and different depositional environments. Detrital zircon age distribution between 653Ma and 1007Ma indicate strong magmatic activities in the southeastern margin of the Yangtze craton and the northern Guangxi Province located in the southwestern Jiangnan orogenic belt, which may be related to amalgamation and breakup of the Rodinia supercontinent, and the 1792~2261Ma magmatic activities are correlated with amalgamation and breakup of the supercontinent Columbia. The 2298~2500Ma detrital zircons are indicative of the Paleoproterozoic basement in the southern margin of the Yangtze craton and a small amount of zircons older than 2500Ma imply the Archean basement in the southern margin of the Yangtze craton there. Absence of 1100~1300Ma Greenville orogenic period records of the 5 samples indicating that the Jiangnan orogenic belt was not located in the center of the Rodinia supercontinent. In short, the southern margin of the Yangtze craton and the southwestern Jiangnan orogenic experienced at least three strong tectono-thermal events, which are well recorded in the Nanhua strata at the northern Guangxi Province. |
| |
| Keywords: | Detrital zircons U-Pb age Nanhua System Jiangnan orogenic belt |
| 本文献已被 CNKI 等数据库收录！ |
| 点击此处可从《岩石学报》浏览原始摘要信息 |
| 点击此处可从《岩石学报》下载免费的PDF全文 |
|
